.TH ll_decode_filter_fid 1 "Dec 15, 2010" Lustre "utilities"
.SH NAME
ll_decode_filter_fid \- display Lustre Object ID and MDT parent FID
.SH SYNOPSIS
.B ll_decode_filter_fid
.I object_file
.RI [ "object_file ..." ]
.br
.SH DESCRIPTION
.B ll_decode_filter_fid
decodes and prints the Lustre OST object ID and MDT FID and stripe index
for the specified OST object(s), which is stored in the "trusted.fid"
attribute on each OST object.  This is accessible to
.B ll_decode_filter_fid
when the OST filesystem is mounted locally as type ldiskfs for maintenance.
.PP
The "trusted.fid" extended attribute is stored on each OST object when it
is first modified (data written or attributes set) and is not accessed or
modified by Lustre after that time.
.PP
The OST object ID (objid) is useful in case of OST directory corruption,
though normally the
.SH EXAMPLE
.fi
root@oss1# cd /mnt/ost/lost+found
.fi
root@oss1# ll_decode_filter_fid #12345[4,5,8]
.fi
#123454: objid=690670 seq=0 parent=[0x751c5:0xfce6e605:0x0]
.fi
#123455: objid=614725 seq=0 parent=[0x18d11:0xebba84eb:0x1]
.fi
#123458: objid=533088 seq=0 parent=[0x21417:0x19734d61:0x0]
.PP
This shows that the 3 files in lost+found have decimal object IDs 690670,
614725, and 533088, respectively.  The object sequence number (formerly
object group) is 0 for all current OST objects.
.PP
The MDT parent inode FIDs are hexdecimal numbers of the form
sequence:oid:idx.  Since the sequence number is below 0x100000000 in
all these cases, the FIDs are in the IGIF (legacy Inode and Generation
In FID) namespace and are mapped directly to the MDT inode = seq and
generation = oid values, so the MDT inodes are
0x751c5, 0x18d11, and 0x21417 respectively.  For objects with MDT parent
sequence numbers above 0x200000000, this indicates that the FID needs
to be mapped via the MDT Object Index (OI) file on the MDT to determine
the internal inode number.
.PP
The idx field shows the stripe number of this OST object in the Lustre
RAID-0 striped file.
.SH SEE ALSO
.BR lustre (7),
